Fork extending construction



July 18, 1961 G. F. QUAYLE FORK EXTENDING CONSTRUCTION 5 Sheets-Sheet 1Filed Aug. 29, 1958 -o sm- I; q 3

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FORK EXTENDING CONSTRUCTION Filed Aug. 29, 1958 5 Sheets-Sheet 4 Wm...""WIHHHH INVEN 1 OR. 'Geoqvsc F Oil/7 YLe' 2,992,751 Patented July 18,1961 2,992,751 FORK EXTENDING CONSTRUCTION George F. Quayle,Philadelphia, Pa., assiguor to The Yale and Towne Manufacturing Company,Stamford, Conn., a corporation of Connecticut Filed Aug. 29, 1958, Ser.No. 757,970 Claims. (Cl. 214-730) This invention relates to anindustrial truck, and more particularly, to an industrial truck adaptedto extend and retract a load relatively to the frame of the truck.

Heretofore, trucks of the class described have been developed in which aleverage system is employed to extend and retract the load, the leversthemselves moving in a vertical plane and resembling spaced pairs ofscissors. In this type of construction, the height of the leveragesystems presents a serious problem. The levers may, for example, occupya vertical space of as much as forty-six inches. Therefore, if a uniformload of, say, thirty inches is to be stacked, it is possible that, dueto interference of the leverage system with overhead structures, anentire course of load units will not be able to be stacked atop lowercourses, therefore wasting a considerable amount of warehouse storagespace.

In order to overcome this serious disadvantage, it was first proposed toconnect a load carrier to a back plate by a leverage system of the classdescribed operating in a horizontal plane. Then, the levers, inextending and retracting the load, will move horizontally. It was soonrealized that such an expedient is completely unsatisfactory because theends of the levers slide toward one another when extending the loadwhile separating when bringing the load toward the truck. Those skilledin the art will immediately appreciate the enormous vertical stressesthat are applied to the levers when the load is extended and the leversare close together. In such a leverage system, instability and twistingmoment produced by an off-center load is extremely serious.

I have conceived by my invention a novel construction that enables me toextend and retract a load carrier without limiting the height to whichthe load carrier may be elevated, while maintaining complete loadstability.

:In essence, my invention resides in the utilization of a leveragesystem employing levers that pivot about vertical axes so that they movein horizontal planes. I am therefore able to obtain the desired amountof extension of my load carrier with a relatively low leverage system.

As a feature of my invention I utilize a separate pair of levers at eachside of the load, the levers at each side being pivoted to one another,while one lever is pivoted to the load carrier and the other to the baseof the truck. Those persons skilled in the art will readily appreciatethat my leverage system in no way limits the amount of lift that I canachieve, so that I am able to obtain maximum vertical lift as well ashorizontal thrust.

As a particular feature of my invention, I pivot to the base plate of mytruck a pair of base levers, and -I utilize a pair of load levers thatare pivoted to the base levers and to the load carrier, all of thepivots being substantially vertical so that the levers swinghorizontally relatively to the base plate.

As another feature of my invention, I employ a ram pivotally connectedthrough substantially vertical pivots between the base plate and one ofthe base levers, and a second ram pivotally connected throughsubstantially vertical pivots between the load carrier and one of theload levers.

Another feature of the invention resides in the utilization of rodsconnected between the base levers and the base plate through an arm thatis pivoted to the base plate and similar rods connected between the loadlevers and the load carrier through an arm that is pivoted to the loadcarrier. By this arrangement, I am able to maintain the load carrierparallel to the base plate regardless of the degree to which the carrieris extended.

I have thus outlined rather broadly the more important features of myinvention in order that the detailed description thereof that followsmay be better understood, and in order that my contribution to the artmay be better appreciated. There are, of course, additional features ofmy invention that will be describedhereinafter and which will form thesubject of the claims appended hereto. Those skilled in the art willappreciate that the conception on which my disclosure is based mayreadily be utilized as a basis for the designing of other structures forcarrying out the several purposes of my invention. it is important,therefore, that the claims be regarded as including such equivalentconstructions as do not depart from the spirit and scope of myinvention, in order to prevent the appropriation of my invention bythose skilled in the art.

A specific embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of an industrial truck utilizing my novelfork extending construction and showing the forks in dot-dash lines inan extended position and in broken lines in an extended, partiallyelevated position;

FIG. 2 is a plan view of the truck shown in FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a front elevation of my invention partially broken away tobetter illustrate certain features;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4; J

FIG. 6 is a side view of my fork extending construction in the positionshown in FIG. 5;

FIG. 7 is a fragmentary side elevation, partly in section, showing mynew construction in extended position;

FIG. 8 is a sectional view taken along the line 88 :of FIG. 7; and

FIG. 9 is a sectional view taken along the line 99 of FIG. 8.

Referring to the drawings, and more particularly to FIGS. 1 and 2, itwill be seen that, for the purpose of description, I have chosen toillustrate my novel truck 10 constructed with a conventional reartraction end .11. This traction end is equipped at opposed sides with adriving and steering wheel '12 and a casterwheel 14. The driving andsteering wheel is controlled by ahan'd Wheel 15 accessible to anoperator. The details of the traction end 11 and its wheel arrangementare not important to an understanding of my invention, it beingnecessary to understand only that the truck is steered and driventhrough its rear end.

For supporting the front end of the truck, I utilize a pair of legs 16and 17 that extend forwardly from the opposite sides of the rear end andthat are each provided with a pair of front wheels 19 and 20*. As willbe readily appreciated by those persons skilled in the :art, thedisposition of the pairs of wheels 19 and 20 in widely spaced relationto one another enable the load to be carried between the wheels, therebycontributing great stability to the truck and enabling one to handleloads in a novel way as will be realized as the description proceeds.

Between the front and rear wheels of the truck, I mount on the truckframe a pair of I beams .21 to serve as primary uprights. Secondaryuprights 22 are movable vertically relatively to primary uprights 21 andare guided by rollers 24 rotatably carried on secondary .uprights 22 andextending into channels in primary uprights 21. Upper cross members 25and 26 are provided on primary and secondary uprights 21 and 22,respectively.

As shown in FIGS. 2 and 3, I utilize a base or back plate 27 forsupporting my extending leverage mechanism and a load carrier, as willbe later described. The base plate has a pair of forwardly extendingbrackets 29 that support rollers 30 for vertical movement in secondaryupright channels whereby the base plate 27 may move verticallyrelatively to the secondary uprights. A hydraulic ram 31 (FIG. 2) servesto elevate the secondary uprights relatively to the primary uprights andthe base plate relatively to the secondary uprights in a manner wellknown in the art.

Referring now to FIGS. 3 and to 8, it will be seen that the base plate27 has four cars 32 projecting from its corners. These ears areapertured to carry a vertical pivot shaft 34 at each side of the backplate. Each of these shafts, in turn, supports a cylindrical sleeve 35one of which has formed integral therewith upper and lower hinge membersor base levers 36, while the other sleeve has similar hinge members orbase levers 37 formed integral therewith. These hinge members areslightly curved outwardly at their ends remote from the sleeves 35, asshown in FIG. 8, and these same ends are recessed to provide a pair offingers 39 formed with holes for the reception of pivot or hinge pins40.

The pins 40 also pass through apertured fingers 41 of hinge members orload levers 42 and 44 that are similar to hinge members or base levers36 and 37, and that are formed integral with cylindrical sleeves 45. Afront plate 46 is provided with upper and lower reinforcing ribs 47 and49 that are shaped at each end to form apertured lugs 50 adjacent theends of the sleeves 45. A vertical pivot shaft 51 passes through each ofthe sleeves 45 and the lugs 50 at the sides of the front plate 46 toconnect the hinge members 42 and 44 to the front plate 46 for pivotalmovement relatively thereto about the vertical shafts 51.

While I have chosen to illustrate the load carrier 52 as a pair of forksmounted on the front plate for movement therewith by means of upper andlower mounting brackets 54 and 55, respectively, it will be understoodthat while my invention is of great utility when used with load forks,the contribution that I have made may be utilized to control theextension of other forms of load carriers as well.

In order to eflect the extension and retraction of the load carrier 52relatively to the base plate 27, I mount the cylinder of a double actinghydraulic ram 56 on a bracket 57 on the front face of the base plate bymeans of a vertical pivot 59. The piston rod 60 of this ram is connectedto a vertical pivot 61 supported in a lug 62 integral with one of thesleeves 35, as shown in FIGS. 3 to 5 and 7 to 9. A similar ram 64extends between the rear face of the front plate 46 to which it isconnected by a bracket 65 and vertical pivot 66, and one of the sleeves45 to which its piston rod 68 is connected by a vertical pivot 67 in alug 69. Attention is here invited to the fact that, as shown, I preferthat the rams be connected to sleeves 35 and 45 that are diagonallyopposite one another.

Referring to FIG. 8, it will be seen that when the ram 56 is actuated toextend its piston rod, the lug 62 and consequently the sleeve 35 on theleft side of the base plate 37, as viewed, will pivot in a clockwisedirection about vertical shaft 34, as will the hinge members 36connected to that sleeve. Similarly, extension of the ram 64 will effectclockwise movement of the hinge members 42 connected to the sleeve 45 atthe right side of the load carrier, as viewed, about the vertical shaft51.

In order to so interrelate the movement of the hinge members 36 and 37,as well as the four hinge members 42 and 44, so that they will beproperly synchronized to obtain a straight line motion of the loadcarrier, or, in other words, to maintain the base plate 27 and the frontplate 46 parallel in all positions of the load carrier, I provide aserpentine shaped reversing link or arm 70 that I connect to the frontof the base plate by a pivot 71. A rod 72 is connected between one endof this link 70 and the vertical pivot 61 by universal joints 74 and 75,respectively. A second rod 76 extends between the other end of the link70 and a vertical pivot 77 supported by a lug 79 integral with the righthand sleeve 35, as viewed in FIG. 8, by universal joints 80 and 81,respectively.

A reversing link 82 is mounted on the front plate by a pivot 84. Rods 85and 86 are connected to opposed ends of the link 82 by universal joints.The other end of rod 85 is universally jointed to the vertical pivot 67in lug 69, and the other end of the rod 86 is universally jointed to apivot 87 carried by a lug 89 that is integral with the left hand sleeve45, as viewed in FIG. 8.

Because of the rods 72, 76, 84 and 85, it will be seen that any motionimparted by rams 56 and 64 to hinge members 36 on the left of the baseplate and to the hinge members 42 on the right of the load carrier, asviewed in FIG. 8, will be duplicated in the opposite hinge members 37and 44. Since the links 70 and 82 reverse the motion of links 72 and 85,it will be apparent that clockwise movement of left hand hinge members36 will be accompanied by equal counterclockwise movement of right hingemembers 37, and that clockwise movement of the right hand hinge members42, relatively to the front plate 46, will be accompanied by equalcounterclockwise movement of left hinge members 44, relatively to thefront plate, for example.

In operation, assuming the parts to be in the position shown in solidlines in FIG. 1, and in FIGS. 2 and 3, it will be understood that theload carrier may lift and transport a load in the usual manner. When itis desired to lift or deposit a load from a space that is too small forthe truck to enter, the rams 56 and 64 are extended so that hingemembers 36 are swung outwardly away from base plate 27. The linkagecomprising rods 72 and 76 and link 70 transmit equal but opposite rotarymovement to hinge members 37 so that they too swing outwardly, away frombase plate 27. At the same time, the ram 64 causes the hinge members 42to swing away from the front plate 47 while the linkage comprising rods85 and 86 and link 82 transmit equal and opposite movement to hingemembers 44 so that the front plate 47, and the load carrier, are thrustoutwardly of the truck 10 to the positions shown, for example, in FIGS.7 and 8 and in dotdash of FIG. 1. It will be seen that during itsmovement, the load carrier front plate 47 is maintained parallel to thebase plate 27. The load carrier may be elevated in any position, asshown by the broken lines of FIG. 1.

Actuation of the rams 56 and 64 to retract the piston rods thereofoperates the hinge members in the opposite manner to that just describedso that the load carrier is retracted relatively to the truck until theparts again assume the position shown in solid lines in FIG. 1, and inFIGS. 2 and 3. Again, the base plate 27 and front plate 47 aremaintained parallel during retraction.

From the foregoing description, it will be seen that I conceived a novelconstruction enabling me to extend a load carrier without limiting theheight to which the load carrier may be elevated. It will also be seenthat the essential characteristic of my invention resides in theutilization of a leverage system employing levers that pivot aboutvertical axes, so as to move horizontally, thereby permitting me toobtain the desired amount of extension, with a relatively low leveragesystem.

I believe that the construction and operation of my novel load extendingconstruction will now be understood, and that the advantage of myinvention will be fully appreciated by those persons skilled in the art.

I now claim:

1. In a truck of the class described, a base plate, a load carrier, apair of base levers each pivoted by a fixed pivot at one end thereof toone side of said base plate on a substantially vertical pivot, laterallyspaced from the fixed pivot of the other base lever a pair of loadlevers, each load lever being pivoted at one of its ends to one of saidbase levers and at its other end to one side of said load carrier on apivot also substantially vertical and laterally spaced from the pivot ofthe other load lever, a ram extending between and operatively connectedto said base plate and a base lever and a second ram extending betweenand operatively connected to said load carrier and a load lever forswinging said levers to move said load carrier between a positionadjacent said base plate and a second position spaced from said baseplate, and means operatively connected with said levers for providingsubstantially simultaneous and equal movement of the levers connected tothe base plate and the levers connected to the load carrier to maintainsaid load carrier parallel to said base plate during movement of saidload carrier toward and away from the base plate.

2. In a truck of the class described, a base plate, a load carrier, apair of base levers each pivoted by a fixed pivot at one end thereof tosaid base plate on a substantially vertical pivot laterally spaced fromthe fixed pivot of the other base lever, a pair of load levers, eachload lever being pivoted at one of its ends to one of said base leversand at its other end to said load carrier on a pivot also substantiallyvertical and laterally spaced from the pivot of the other load lever,and a ram extending between and operatively connected to said base plateand a base lever and a second ram extending between and operativelyconnected to said load carrier and a load lever to move said loadcarrier between positions adjacent said base plate and spaced from saidbase plate, and means operatively connected to said levers formaintaining said load carrier parallel to said base plate in allpositions thereof.

3. In a truck of the class described, a base plate, a load carrier, apair of base levers each pivoted at one end thereof to said base plateon a substantially vertical pivot at a point laterally spaced from theother base lever, a pair of load levers, each load lever being pivotedat one of its ends to one of said base levers and at its other end tosaid load carrier on a pivot also substantially vertical and laterallyspaced from the pivot of the other load lever, a ram extending betweenand operatively connected to said base plate and a base lever and asecond ram extending between and operatively connected to said loadcarrier and a load lever to move said load carrier between positionsadjacent said base plate and spaced from said base plate, a linkpivotally connected to said base plate, a pair of rods pivoted at oneend to opposed ends of said link and at their other ends to opposed baselevers, a second link pivotally connected to said load carrier, and apair of rods pivoted at one end to opposed ends of said second link andat their other ends to opposed load levers whereby said load carrier isin all positions thereof maintained parallel to said base plate.

4. In a truck of the class described, a base plate, a load carrier, apair of base levers each pivoted by a fixed pivot at one end thereof tosaid base plate on a substantially vertical pivot laterally spaced fromthe vertical pivot of the other base lever, a pair of load levers, eachload lever being pivoted at one of its ends to one of said base leversand at its other end to said load carrier on a pivot also substantiallyvertical and laterally spaced from the pivot of the other load lever, aram connected through substantially vertical pivots between said baseplate and a base lever and a second ram connected also throughsubstantially vertical pivots between said load carrier and a load leverto move said load carrier between positions adjacent said base plate andspaced from said base plate, a link pivotally connected to said baseplate, a pair of rods pivoted at one end to opposed ends of said linkand at their other ends to opposed base levers, a second link pivotallyconnected to said load carrier, and a pair of rods pivoted at one end toopposed ends of said second link and at their other ends to opposed loadlevers whereby said load carrier is in all positions thereof maintainedparallel to said base plate.

5. In a truck of the class described, a base member, a load carrier, apair of base levers each pivoted at one end thereof to said base memberon a substantially vertical pivot laterally spaced from the verticalpivot of the other base lever, a pair of load levers, each load leverbeing pivoted at one of its ends to one of said base levers and at itsother end to said load carrier on a pivot also substantially verticaland laterally spaced from the pivot of the other load lever whereby saidload carrier may be extended and retracted relatively to said basemember by horizontal folding movement between said base levers and saidload levers, and means operatively connected with said load carrier,base member, and said levers for extending and retracting said loadcarrier and determining the position of said load carrier relatively tosaid base member during such extension and retraction of said loadcarrier.

References Cited in the file of this patent UNITED STATES PATENTS518,633 Steur Apr. 24, 1894 892,413 Freeman July 7, 1908 2,471,901 RossMay 31, 1949 2,639,051 Thomas May 19, 1953 2,752,058 Gibson June 26,1956 2,896,806 Vossenberg July 28, 1959

